What "Best By," "Sell By," and "Use By" Actually Mean

Three Labels, Three Different Jobs

A carton of milk, a bag of chips, and a jar of mayonnaise can each carry a different date label — "best by," "sell by," "use by" — and most people treat all three the same way: as an expiration date. They're not the same thing, and mixing them up is the single biggest reason good food ends up in the trash.

"Best By" is about taste, not safety

"Best by" is a manufacturer's estimate of peak quality. Past that date, a food is very likely still fine to eat — it just might not taste quite as fresh, crisp, or flavorful as it did on day one. A bag of chips a week past its "best by" date isn't dangerous. It might just be slightly stale.

This label exists to protect a brand's reputation for quality, not to protect a person from getting sick. That distinction is the whole reason this label causes so much confusion — it looks exactly like a safety warning, and it isn't one.

"Sell By" is a note to the store, not to you

"Sell by" tells a retailer how long to display a product before pulling it — it's inventory management, aimed at the store, not the shopper. A product can be entirely good to eat well past its "sell by" date. This label was never meant to reach the person eating the food at all; it just ends up printed somewhere the customer can see it.

"Use By" is the one that actually signals a real limit

"Use by" is the closest of the three to an actual safety marker — it's the date a manufacturer considers the last point at which a product should be consumed at its intended quality and, for some foods, safety. This is the one date genuinely worth paying closer attention to, especially on perishables like deli meat, soft cheese, or infant formula, where the margin between "fine" and "not fine" narrows fast.

Even here, though, "use by" is still a manufacturer's estimate, not a guarantee. A food can go bad before its "use by" date if it was mishandled, or stay perfectly good past it if it was stored well.

Why none of these labels are actually testing your food

Here's the part that trips almost everyone up: none of these three labels are based on your food, your fridge, or how it was actually handled after you bought it. They're all fixed estimates set at the moment of manufacturing, under ideal, standardized conditions.

A "best by" date doesn't know your refrigerator has been running two degrees warmer than it should. A "use by" date doesn't know the deli meat sat in a hot car for twenty minutes on the way home. The label is a starting estimate. What actually happened to the food after that point is invisible to the date printed on the package.

What actually tells you more than the date does

Smell, texture, and appearance carry real information the date can't. A sour or "off" smell, a slimy texture, visible mold, or a swollen or leaking package are all signals the label was never designed to give you, and they matter more than whatever's printed on the box.

For high-risk foods specifically — raw meat, poultry, fish, dairy, deli items, soft cheeses — the safer habit is treating the "use by" date as a real outer limit rather than a suggestion, since these are exactly the foods where harmful bacteria can grow without any obvious smell or visible change at all.

Why this labeling mess exists in the first place

These three phrases aren't standardized by law in most places, which is exactly why a carton of eggs and a jar of pickles can carry completely different label language without any consistent meaning behind the wording itself. Each manufacturer picks its own phrasing, largely for its own purposes — quality assurance, inventory turnover, liability — not for a shopper trying to make a food-safety decision at the fridge.

That's the real source of the confusion driving so much unnecessary food waste: three phrases that sound almost interchangeable, doing three genuinely different jobs, printed with no consistent rule across brands or products.